Solution to the Multidepot Inventory Slack-Routing Problem at the Planning Stage

Abstract

To help governments improve preparedness for emergency events, this study introduces a solution framework for the multidepot inventory slack-routing problem (ISRP). By defining slack as the difference between delivery arrival time and estimated inventory stock-out time, the objective of ISRP is to maximize the inventory slack of each dispensing site. Previous studies exclusively focused on single-depot ISRP, but this study extends the problem to a multidepot case, which is more applicable in practice. To quickly generate an optimal solution, this study proposes an efficient solution heuristic that consists of four consecutive steps: site assignment, vehicle routing design, delivery quantity scheduling, and site reassignment. The numerical test demonstrates that the proposed heuristic can properly assign the dispensing sites to different depots, design optimal vehicle routing plans for each depot, and balance inventory slacks over all sites.